How to install Claude Code [Windows and Mac] — API key configuration without a subscription and payment with JCB and Apple Pay

Installing Claude Code requires only running one line from the official native installer. Use install.sh for Mac, Linux, and WSL; install.ps1 for Windows PowerShell; and install.cmd for CMD (npm also works, but requires Node.js 22 or later). Normally you then log in with a Pro or Max plan, but without a subscription you can launch without logging in by setting ANTHROPIC_BASE_URL=https://api.kunavo.com (without adding /v1), ANTHROPIC_AUTH_TOKEN containing the API key, and the four model-pinning variables. Confirm that it works with /status. API balance can be prepaid from $10 with cards such as JCB, Apple Pay, Google Pay, and Link; the payment page displays amounts in yen.

# macOS・Linux・WSL
curl -fsSL https://claude.ai/install.sh | bash

# Windows PowerShell
irm https://claude.ai/install.ps1 | iex

:: Windows コマンドプロンプト（CMD）
curl -fsSL https://claude.ai/install.cmd -o install.cmd && install.cmd && del install.cmd

The primary sources for installation instructions are Anthropic’s official documentation, available in Japanese (Setup, Installation troubleshooting, checked on October 3, 2026). Rather than repeat that content, this page focuses on points that Japanese-language explanatory articles get wrong (the Node.js version, Windows administrator privileges, and Git), as well as topics the official documentation does not cover—configuring Claude Code to run with an API key without signing in, and paying from Japan. Pricing and payment methods are current as of October 10, 2026. Japan is listed as a supported country for both Claude.ai and the API in Anthropic’s list of supported countries (checked on October 3, 2026).

Decide first: log in with a subscription or run with an API key

The installation itself is the same either way; the difference comes after the first launch. Claude Code asks for authentication when it starts. If you are unsure, use these three criteria:

• Already subscribed to Pro, Max, Team, or Enterprise, or have a Console account: log in directly to use it. You do not need the API-key settings on this page. The Free plan does not include Claude Code.
• You do not want to pay a fixed monthly fee, and your usage varies greatly from month to month: running it with an API key and paying only for the tokens you use may suit you. For reference, Claude subscriptions cost $20 per month for Pro ($200 per year, equivalent to $17 per month) and start at $100 per month for Max; both prices exclude tax (Claude pricing page, checked on October 3, 2026). The Claude Code pricing guide estimates the point at which one option becomes cheaper than the other.
• You want to use Remote Control or voice input: both require a claude.ai account and cannot be used with an API key. Choose login.

The payment methods also differ. Subscriptions purchased on Anthropic’s website can be paid for only by credit or debit card; subscriptions purchased through the iPhone or Android app are billed by the App Store or Google Play (Anthropic Help, English version, checked on October 3, 2026). You can top up your Kunavo API balance with cards, including JCB, Apple Pay, Google Pay, or Link (see the payment section later in this guide).

Pre-installation check

The requirements are as stated in the official documentation (checked on October 3, 2026). The right column explains how to check them locally.

Which installation method to use

The official documentation recommends the native installer. The main difference from other methods is how updates are handled.

# Homebrew（既定では自動更新されない）
brew install --cask claude-code

# WinGet（Windows・既定では自動更新されない）
winget install Anthropic.ClaudeCode

For any method, reopen the terminal after finishing, then check. Windows that were open before installation may not have loaded the new PATH. claude doctor displays only the installation and configuration status without starting a session, so it is useful for troubleshooting.

claude --version   # 2.1.211 (Claude Code) のようなバージョン番号が出れば OK
claude doctor      # セッションを開かずに、インストールと設定を診断する

Notes for npm installation

Japanese-language explanatory articles often still say “Node.js 18 or later,” but the official documentation requires Node.js 22 or later (official documentation, checked on October 3, 2026). With an older Node.js version, npm only displays an EBADENGINE warning and does not stop the installation, and claude still launches, but it is safer to upgrade Node.js when you see the warning. If you use nvm, Volta, or another tool to switch versions, check node -v in the shell where you install it.

node -v                                    # v22 以上であること
npm install -g @anthropic-ai/claude-code   # sudo は付けない

# 更新は @latest で（npm update -g は使わない）
npm install -g @anthropic-ai/claude-code@latest

The official documentation explicitly says not to use sudo npm install -g. The main binary is installed as an optional dependency, so if --omit=optional or .npmrc's optional=false omits optional dependencies, macOS/Linux displays claude native binary not installed and cannot start.

Key points for installing on Windows

First, two steps often recommended online are unnecessary. “Run PowerShell as an administrator” and “install Git for Windows first” are both absent from the official documentation’s requirements. Administrator privileges are not required, and Git for Windows is optional; if it is not installed, Claude Code runs commands in PowerShell (Setup on Windows, checked on October 3, 2026).

Before pasting a command, check just two things.

1. Are you currently in PowerShell or CMD?If the prompt is PS C:\Users\ユーザー名>, use the PowerShell irm line; if it is C:\Users\ユーザー名> without PS, use the CMD install.cmd line. Mixing them up produces an error in PowerShell saying && is not recognized as a separator, or in CMD saying irm is not recognized (on Japanese Windows, the messages may appear in Japanese).
2. Did you open “Windows PowerShell (x86)”?The (x86) entry in the Start menu runs as a 32-bit process, so even on a 64-bit computer it stops with Claude Code does not support 32-bit Windows.

There are three ways to run it on Windows. If unsure, starting natively is fine.

If Git for Windows is installed but Claude Code cannot find Git Bash, set bash.exe to the location of CLAUDE_CODE_GIT_BASH_PATH in env in the user settings file.

{
  "env": {
    "CLAUDE_CODE_GIT_BASH_PATH": "C:\\Program Files\\Git\\bin\\bash.exe"
  }
}

When claude does not work after installation

'claude' is not recognized (on Mac/Linux, command not found: claude) means the installation directory is not in PATH. The native install location is %USERPROFILE%\.local\bin\claude.exe on Windows and ~/.local/bin/claude on Mac/Linux. If reopening the terminal does not fix it, follow the official documentation to check and add it from PowerShell.

# 1. インストール先が PATH に入っているか確認する
$env:PATH -split ';' | Select-String '\.local\\bin'

# 2. 何も出なければユーザーの PATH に追加し、ターミナルを開き直す
$currentPath = [Environment]::GetEnvironmentVariable('PATH', 'User')
[Environment]::SetEnvironmentVariable('PATH', "$currentPath;$env:USERPROFILE\.local\bin", 'User')

# 3. 新しいターミナルで
claude --version

If you installed with npm and see npm.ps1 cannot be loaded because running scripts is disabled on this system (or claude.ps1 when launching), PowerShell’s execution policy is blocking npm’s .ps1 script (official documentation, checked on October 3, 2026). Resolve this by running the following command, which allows local script execution for the current user only. If you do not want to change the policy, use npm.cmd or claude.cmd, or switch to the native installer for PowerShell.

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

Configure it to run with an API key without logging in

Kunavo is an independent API gateway, not Anthropic, that provides prepaid API access to models such as Claude. Claude Code officially supports a variable called ANTHROPIC_BASE_URL for changing the destination, and the official documentation has a page titled “Connect Claude Code to an LLM gateway.” No plugins or modified versions are required. This variable changes only the destination; a separate variable determines which model responds (Model configuration, checked on October 3, 2026).

Configure these six items.

On Mac/Linux, append it to the shell configuration file (~/.zshrc or ~/.bashrc) and reopen the terminal.

export ANTHROPIC_BASE_URL=https://api.kunavo.com   # ドメインだけ。/v1 は付けない
export ANTHROPIC_AUTH_TOKEN=sk-kn-...
export ANTHROPIC_MODEL=claude-sonnet-5
export ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-5-5
export ANTHROPIC_DEFAULT_SONNET_MODEL=claude-sonnet-5
export ANTHROPIC_DEFAULT_HAIKU_MODEL=claude-haiku-4-5

To test it on Windows, run the following in a PowerShell window. It disappears when you close the window.

# このウィンドウの中だけで有効（閉じると消える）
$env:ANTHROPIC_BASE_URL = "https://api.kunavo.com"
$env:ANTHROPIC_AUTH_TOKEN = "sk-kn-..."
$env:ANTHROPIC_MODEL = "claude-sonnet-5"
$env:ANTHROPIC_DEFAULT_OPUS_MODEL = "claude-opus-5-5"
$env:ANTHROPIC_DEFAULT_SONNET_MODEL = "claude-sonnet-5"
$env:ANTHROPIC_DEFAULT_HAIKU_MODEL = "claude-haiku-4-5"
claude

If you do not want to enter it every time, put it in env in the user settings file ~/.claude/settings.json (on Windows, %USERPROFILE%\.claude\settings.json). It applies to all projects and uses the same format on Mac and Windows. If the file already has other settings, add only the env block.

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://api.kunavo.com",
    "ANTHROPIC_AUTH_TOKEN": "sk-kn-...",
    "ANTHROPIC_MODEL": "claude-sonnet-5",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "claude-opus-5-5",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-5",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-haiku-4-5"
  }
}

Three notes about where to put it

• .claude/settings.json in your project should not contain a key. It is committed to the repository and shared with everyone who clones it (official documentation).
• If the same variable exists in both the shell and settings file, the settings-file value is used. If it does not change after running export again, check the settings file.
• When using the VS Code extension, put the same variables in claudeCode.environmentVariables in VS Code user settings.

Why use ANTHROPIC_AUTH_TOKEN

ANTHROPIC_AUTH_TOKEN is sent in the Authorization: Bearer header and becomes effective immediately. ANTHROPIC_API_KEY is sent in the x-api-key header and, in interactive mode, asks once for approval to use it. If you reject it, the key is silently ignored afterward and remains unused until re-enabled through /config's Use custom API key. Kunavo accepts keys sent in either header, so ANTHROPIC_API_KEY also works, but ANTHROPIC_AUTH_TOKEN is more reliable because it avoids this pitfall. The official documentation also recommends ANTHROPIC_AUTH_TOKEN when the key type is unspecified.

Why pin the models (as of October 3, 2026)

According to the official documentation (checked on October 3, 2026), when using an API key, the default model and the opus alias point to Opus 5.5, while the sonnet alias points to Sonnet 5.5. Alias targets change when new models are released, but they are not necessarily available on Kunavo on the same day. In fact, Kunavo does not offer Sonnet 5.5 as of October 3, 2026, so choosing /model sonnet without pinning the model results in a 404. The execution phase of opusplan and subagents configured with model: sonnet are affected too. That is why the configuration above also pins the sonnet alias using ANTHROPIC_DEFAULT_SONNET_MODEL=claude-sonnet-5. The opus alias is also pinned to Claude Opus 5.5 with ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-5-5, so it will continue to work even if its target changes to the next Opus model. Claude Opus 5.5 requires Claude Code v2.1.280 or later, so update an older version with claude update.

Pinning the model also makes costs easier to predict. If you do not specify one, the default model is Claude Opus 5.5, which has a higher per-token price than using Claude Sonnet 5 as the main model. Kunavo’s rates per 1 million tokens, input / output, are Claude Haiku 4.5 at $0.70 / $3.50, Claude Sonnet 5 at $1.40 / $7.00 (Anthropic pricing is $2.00 / $10.00), and Claude Opus 5.5 at $2.80 / $14.00. If you do not set ANTHROPIC_DEFAULT_HAIKU_MODEL, background tasks such as conversation summarization for claude --resume also run on the main model in sessions started with ANTHROPIC_AUTH_TOKEN (Gateway compatibility guide, checked on October 3, 2026). Anthropic’s pricing page has moved Sonnet 5, which is pinned as the main model, to the “Legacy models” section (checked on October 3, 2026).

Verify operation in three stages

1. Test only the URL and key before launching

This is the same request as in the official documentation, with only 1 output token (a very small amount is deducted from the balance). Because it reads shell variables, if you have written the key only in a configuration file, run export in this terminal before executing it. If JSON beginning with {"id":"msg_ and 200 are returned, both the URL and key are working; 401 means the key was rejected.

curl -sS -w '\n%{http_code}\n' -X POST "$ANTHROPIC_BASE_URL/v1/messages" \
  -H "Authorization: Bearer $ANTHROPIC_AUTH_TOKEN" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model": "claude-sonnet-5", "max_tokens": 1, "messages": [{"role": "user", "content": "."}]}'

For PowerShell, use the following; if the returned id begins with msg_, it succeeded.

Invoke-RestMethod -Method Post -Uri "$env:ANTHROPIC_BASE_URL/v1/messages" `
  -Headers @{ "Authorization" = "Bearer $env:ANTHROPIC_AUTH_TOKEN"; "anthropic-version" = "2023-06-01" } `
  -ContentType "application/json" `
  -Body '{"model": "claude-sonnet-5", "max_tokens": 1, "messages": [{"role": "user", "content": "."}]}'

2. Launch claude and verify that no login screen appears

On the first run, the initial setup wizard and folder trust confirmation appear, but you will not be asked to log in through a browser afterward. If you are asked to log in, the key has not been received.

A common cause is that the key has been written only to the project's .claude/settings.json or .claude/settings.local.json. In an interactive session, the project setting env is loaded after the wizard and folder trust confirmation are complete, so the key is treated as unavailable at initial launch. Move it to the shell's export or the user's ~/.claude/settings.json.

3. Check the two lines in /status

Run /status within the session, then check the Status tab (official documentation, checked on October 3, 2026).

• Anthropic base URL should show https://api.kunavo.com. This line appears only when the gateway has been configured, so if the line itself is missing, ANTHROPIC_BASE_URL has not reached the session.
• Auth token should show ANTHROPIC_AUTH_TOKEN. If instead the claude.ai account's Login method appears, it is running with a saved login.

What changes when running with an API key

• Remote Control and voice input are unavailable. Both require a claude.ai ID, so they are disabled while gateway credentials such as ANTHROPIC_AUTH_TOKEN are active. Starting with v2.1.196, Remote Control is disabled simply when ANTHROPIC_BASE_URL points to a non-Anthropic host.
• /fast is shown as disabled. When authenticating with only a bearer token, Claude Code treats fast mode as disabled without checking whether it is available and displays Fast mode has been disabled by your organization.
• The figures in /context are estimates. Because Kunavo does not provide /v1/messages/count_tokens, Claude Code switches to estimating based on character count (Gateway compatibility guide, checked on October 3, 2026).

Detailed Kunavo configuration is available in the Claude Code integration documentation and the ANTHROPIC_BASE_URL documentation (both in English).

Paying for API balance: JCB, Apple Pay, Google Pay, and Link

Here are the points most commonly asked about when paying from Japan.

There are 4 steps. First, sign up for Kunavo (with an email address or Google account; card details are not requested during registration). Next, select the top-up amount in Billing on the dashboard. The minimum is $10; there are no monthly fees, and larger amounts receive a bonus ($100 for a $110 balance, $1,000 for a $1,200 balance, and $5,000 for a $6,250 balance). After selecting one of the methods above and paying on the Stripe checkout page, finally create a API Keys key with sk-kn- and enter it in ANTHROPIC_AUTH_TOKEN. The key is displayed only once when created, so copy it immediately.

The balance does not expire, and failed requests are not charged. The payment methods available for paying for a Claude subscription in Japan (including through the App Store and Google Play) are summarized with sources in Claude payment methods.

Estimated costs

Claude Code run with an API key uses pay-per-token billing. Claude Code sends the entire conversation context with each request, but the same leading portion as in the previous request may be billed at the cache-read rate. The table below assumes 40,000 input tokens per request, of which 36,000 = 90% are cache reads and the remaining 4,000 are cache writes, 1,000 output tokens, and 50 requests per task. Background Claude Haiku 4.5 calls are not included. For Claude Sonnet 5, Kunavo's cache rates are 10% of the input rate for reads and 1.25 times the input rate for writes (each model in the table is calculated using its respective ratio). These are neither measured values nor upper limits.

The actual amount varies with context length, cache effectiveness, response length, and whether you /clear for each task. Unit prices for all models are available on the pricing page; estimates based on your usage are available through the Claude token cost calculator (in English), and model-specific API prices are listed in Claude API pricing.

Common errors and solutions

When this method is not suitable

• Qualified invoices are required for expense reimbursement. Kunavo Checkout does not issue invoices or qualified invoices with a registration number.
• I want to pay with convenience-store payment or PayPay. Neither is supported, nor are bank transfers or carrier billing. Automatic top-ups work only with a saved card or Link.
• I want to use Remote Control or voice input. They are unavailable with an API key, and /fast is also shown as disabled. Log in with a subscription.
• I want to use Sonnet 5.5. Kunavo does not provide it as of October 3, 2026.
• I want to complete the configuration using Japanese documentation only. The official Claude Code documentation is available in Japanese, but Kunavo's integration documentation is available only in English.

What to do next

Once you have confirmed it with /status, launch claude in the directory of the project you will work on, then first create CLAUDE.md with /init. How to use Claude Code explains in order what to write in CLAUDE.md, how to reduce confirmation dialogs, and how to create custom commands.

Frequently asked questions